I use both and like both but if I were forced to choose one, it would be the Sweat Gutr.

In hot, humid oppressive summer weather, the Gutr is better since it doesn't saturate completely like the Halo.

On shorter rides or in less oppressive heat, I like the Halo just as much. It fits a little easier under a helmet

I would give the Sweat Gutr an A+ and the Halo an A-

Dan